Epicyclic fluid flow apparatus



iled Aug. 28, 1935 4 Sheets-Sheet 1 INVENTGR Filed Aug. 28 1935 ENVENTORMarch 29, 1938, L. F. MOODY EPICYCLIC FLUID FLOW APPARATUS Filed Aug.28, 1935 4 Sheets-Sheet 3 v aura INVENTQR F. MOQDY 2,1123% arch 29, W38,

EPIGYCLIC FLUID FLOW APPARATUS A Sheets-Sheet 4 Filed Aug. 28, 1955Patented Mar. 29, 1938 UNITED srares ATENT OFFIQE 2,112,300 EEECYCIJCFLUID FLOW APPARATUS Lewis Ferry Moody, Princeton, N. J. ApplicationAugust '28, 1935, Serial No. 38,162

10 illaims.

This invention relates generally to fluid propelling and fluid powergenerating apparatus of the blade type and more particularly to improvedmeans for minimizing the possibility of friction between the blades andfluid flowing thereover, the invention being particularly applicable tohydraulic turbines, pumps and propellers wherein the hydraulic frictionmay be of appreciable magnitude.

The history of hydraulic turbine and pump practice shows a continuedstruggle to increasethe permissible speeds of rotation of the revolvingelement, to make them suited to the speeds attainable in the electricgenerators of motors to which they are usually coupled, and to reducethe weight and cost of the machinery and surrounding structure.Particularly in adapting the machines to low heads and large waterquantities the question of speed becomes of major importance, oftenjustifying aconsiderable sacrifice in efficiency to attain a high speed.The propeller type turbine and pump using high relative velocitiesbetween the runner blades and the water have accomplished a notableincrease in rotational speed.

Employing these high relative velocities, however, necessitates a highsurface resistance and loss of head which not only impairs efiiciency,but erTectually resists any effort toward further speed increases; andthe attempt to reduce this resistance by employing narrow blades ofreduced area has been ineffective beyond a certain point and if carriedtoo far results in cavitation, pitting and instability and loss ofeificiency without matcrial increase in speed. I, therefore, haveintroduced a method of eliminating a large portion of this loss by achange in the whole method of action between the blades and fluid. Thisnew principle is applicable to hydraulic turbines, pumps, reversiblepump-turbines, air blowers, marine propellers or any machine utilizingthe interaction of moving blades and flowing fluid; but is illustratedhere as applied to specific machines or elements, and particularlyillustrated in a hydraulic turbine.

According to the principle of this invention, while the conformation ofthe blades remains fixed with respect to the hub of the runner orrevolving element, the actual material and, therefore, the surface ofeach blade moves backwardly with respect to the motion of the hub and ofthe runner as a whole, so that the relative velocity between fluid andblade surface is reduced. This is accomplished by forming the blades aspivoted circular disks properly cupped or curved in planes containingthe pivot axis to provide the proper hydraulic contour, and mounting thepivots in bearings carried by the runner hub so that each blade is freeto rotate with respect to the hub and shaft of the runner. When leftfree to rotate relatively to the runner as a whole, each disk willautomatically endeavor to assume that speed of relative rotation whichwill give a minimum frictional drag from the working fluid, thusminimizing the resistance opposing rotation of the runner and at thesame time minimizing the disturbance set up in the flowing fluid andloss 'of head due to eddies.

The source of surface friction resistance is in the boundary layer offluid in contact with and close to a surface along which it flows. Ifthe surface can move with the fluid this source of loss and turbulenceis eliminated. Moreover, the drag or tangential friction force isclosely proportional to the square of the relative velocity, so that ifthe relative velocity is reduced to onehalf its original value, the dragor frictional force is reduced to only about one-quarter of its previousamount. Consequently it is not necessary to reduce the relative velocityto zero at all points; but any material reduction in velocity will bereflected in a much greater proportional reduction in friction and lossof energy. The complete runner or rotating element of this inventioninvolves an epicyclic action (sometimes termed a planetary motion) -aseries of blades or disks which rotate relatively to the revolvingsystem at the same time that the system itself revolves. Any point on ablade traces in space an absolute path which is epicycloidal incharacter. It is, of course, necessary to modify the blades peripheralcontour somewhat to make it circular, thus cutting away its outercorners farther than is usually done in the case of turbines and pumps.This is partly compensated by increasing somewhat the number ofblades-say from four to six or eight, and allowing considerable overlapin the inner portions near the hub, which is not objectionable. Theblades are also inclined at a smaller angle,

relatively to a plane normal to the runner axis,-

than is usual in turbines and pumps; that is, the blades are given asmaller pitch than usual, in speaking of a marine propeller. This ispermissible since a higher speed of runner rotation is to be attained.The new type of runner here described is particularly adapted to veryhigh specific speeds.

Certain portions of the boundary wall of the fluid passages usuallycomprising portions of the stationary elements of a. turbine or pump mayalso when desired follow the principle here described, that is, they maybe made freely rotatable to permit them to take up automatically amotion minimizing the wall resistance of the flowing medium. The sameprinciple may also be applied to the conical end or other portions ofthe runner or propeller itself, this cone or portion being mounted. on abearing coaxial with the runner so that it is free to revolve at a speeddifferent from that of the runner proper.

The principle of the invention will be better understood by referring tothe following descriptions of illustrative embodiments, in which:

Fig. l is a sectional elevation of an axial-flow hydraulic turbinerunner and surrounding elements;

Fig. 2 is a partial l, on line 2-2 of Fig. 1;

Fig. 3 is a section of one of the blades of the runner of Fig. l in aplane containing the pivot axis of the blade;

Fig. 4 is a sectional elevation of the powerhouse containing the turbineof Figs. 1-3;

Fig. 5 is a sectional elevation of a diagonalflow hydraulic turbinerunner and surrounding parts;

Fig. 6 is a sectional elevationrof a horizontalshaft pump, turbine orreversible pump-turbine;

Fig. 7 is a sectional elevation of a verticalshaft pump.

In the turbine of Figs. 1 to 4 the water enters from the spiral casing Iof usual form, passes between the stay vanes 2, pivoted guide vanes orwicket gates 3, flows through the transition space 4, runner 5 and intothe draft tube 6. The head cover 1 supports the main shaft bearing 8,stuffing box 9, and guide vane operating mechanism W. The main shaft His coupled to, or continued to form, the shaft I2 of the generator [3,where it is supported by a thrust and guide bearing. At its lower end itis bolted to the hub M of the runner 5. This hub carries a series ofinclined bearings 15 in which are rotatably supported the pivots E6 ofthe blades or disks l1. These blades have their outermost portionsexposed to the flowing fluid which drives the runner by acting on them.Their inner portions are within the hollow hub I I which is filled withidle water. The blades or disks pass through slots formed to receivethem without touching them, a small clearance being provided. It will beunderstood that in passing through the dead water within the hub duringtheir relative rotation the blades will suffer a certain amount ofretarding drag, but less than the forward drag from the active flowoutside, so that the blades will automatically assume a mean velocityminimizing the total drag, or balancing the forward and backward forces.Furthermore, the active surface forces near the outermost limits of therunner, where the blades encounter the highest relative velocities, willexert a large moment to rotate the vanes on account of the largeeffective lever arm about the pivots, so that the final velocity ofrelative rotation will tend to accommodate itself to the rapidly movingpart of the flow. That part of the flow near the hub surface will becomparatively little effected by the blade rotation, but here therelative velocities and resistances are very much less than in theregion of the blade tips or outermost portions. The net result will be amaterial reduction in the average relative velocity between blades andflowing water, and a still greater proportional reduction in drag andloss of head.

The bearings section of the runner of Fig.

l5 for the pivots are shown with removable portions permitting the readyassembly or removal of the blade disks.

In Fig. 1 (not shown in Fig. 4) is illustrated the method of furtherreducing the resistance to flow by making the inner wall l8 of thetransition space 4 movable. Although this provision is not as importantas the blade rotation, since the absolute velocity of flow along thiswall is much less than the relative velocity of the runner blades, itmay be used in addition to reduce the Wall friction opposing flow andthe consequent turbulence propagated in the flow. The portion I8 isfreely rotatable, supported by the bearings shown, either ball bearingsas indicated or plain journal bearings.

In Fig. 1 the draft tube is of the spreading type with central core orcone registering with the runner. This type is advantageous when unitspacing permits its use, particularly with the large diameter hub hererequired. This hub diameter is of the same general proportions as inmany turbines of the Kaplan or adjustable blade type, and the relativelylarge size has not been found prohibitive.

In Fig. 4 the same turbine as in Fig. l is shown in connection with anelbow draft tube. Here, if desired, the lower conical end IQ of therunner hub can be made freely rotatable, carried by a journal bearing ona stub shaft mounted in the bottom wall of the hub.

In Fig. 2, 12 indicates the absolute velocity of the runner hub androtating system; q indicates the backward relative velocity of the bladedisk. At any point, the effective relative surface velocity will be11-11, 1) being the relative velocity of the system or of a non-rotatingblade with respect to the water, or of the water with respect to theblade. If at a point in the outer portion of the blade q assumes a valueof say 42.3% of v, the effective surface velocity will be 57.7% of v andthe frictional drag will be only one-third of that with a fixed blade.

In Fig. 6 my improved runner is applied to a horizontal shaft hydraulicapparatus adapted to function either as a pump, turbine or reversiblepump-turbine while in Fig. '7 the runner is applied to a vertical shaftpump. The foregoing construction may embody any of the features of theother modifications, but preferably the Fig.

6 runner is the same as shown in Fig. 1, while the Fig. 7 runner is thesame as Fig. 4 and accordingly carries the same reference numbers.

In Fig. 6 the runner or impeller 5 operates within a space between twosets of guide vanes, 20, 2|. When operating as a pump, vanes 20 areguide vanes directing the flow to the runner and 2| are diffusion vanesdecelerating the flow therefrom. When operating as a turbine, thedirections of flow and runner rotation are reversed.

In Fig. '7, the flow is upward between the guide or stay vanes 22,through the impeller 5, and the diffusion vanes 23.

From the foregoing disclosure, it is seen that I have provided veryeffective means for minimizing frictional resistance between the morevital portions of the apparatus such as the blades or a portion of thewall forming the transition space. It will of course be understood thatvarious changes in details of construction and arrangement of parts maybe made by those skilled in the art without departing from the spirit ofthe invention as set forth in the appended claims.

I claim:

1. Fluid apparatus comprising, in combination,

a rotor hub rotatable about a fixed axis and having overlapping bladesdirectly supported by said hub, said blades normally rotating in onlyone direction relative to the hub during rotation thereof, and meansforming a passage in which said rotor operates.

2. Fluid apparatus comprising, in combination, a rotor having a hubrotatable about a fixed axis and blades supported directly by said huband continuously movable in one direction relative thereto duringrotation thereof, and means forming a fluid passage in which said rotoris coaxially disposed.

3. Fluid apparatus comprising, in combination, a rotor hub rotatableabout a fixed axis and having disc blades supported directly by said huband individually rotatable relative thereto during rotation thereof, andmeans forming a fluid passage in which said rotor is coaxially disposed.

4. Fluid apparatus comprising, in combination, a rotor having a hubrotatable about a fixed axis and disc blades supported directly by saidhub, means for supporting the blades for continuous rotation relative tothe hub, and means forming a fluid passage in which said rotor iscoaxially disposed whereby said disc blades rotate during flow of fluidthereover thereby to minimize surface friction between the blades andfluid.

5. Fluid apparatus comprising, in combination, a rotor having a hubrotatable about a fixed axis and disc blades supported directly by saidhub means for supporting said discs by said hub for continuousuni-directional rotation! about inclined axes, and means forming a fluidpassage in which said rotor is coaxially disposed.

6. Fluid apparatus comprising, in combination, a rotor having a hubrotatable about a fixed axis and blades supported directly by, said huband continuously revoluble relative thereto during fluid flow over saidblades, the opposite sides of said blades having different contours, andmeans forming a fluid passage in which said rotor is coaxially disposed.

7. Fluid apparatus comprising, in combination, a rotor having a circularhub with recesses therein, disc blades having one portion disposedwithin said recesses and another portion projecting outwardly from thesurface of said hub, and means for supporting said blades for continuousunidirectional rotation.

8. Fluid apparatus comprising, in combination, a rotor having a circularhub with recesses therein, disc blades having one portion disposedwithin said recesses and another portion projecting outwardly from thesurface of said hub, and means for supporting said disc blades forcontinuous rotation in the same direction relative to said hub.

9. In a hydraulic turbine, in combination, a rotatable hub, a series ofrelatively flat circular disks pivotally mounted in said hub androtatable relatively thereto about axes different from the axis ofrotation of said hub; said disks passing through slots in the hub wallformed to provide small clearance around said disks, and the axis ofsaid disks being inclined in a direction more nearly perpendicular thanparallel to a plane normal to the axis of rotation of the hub.

10. In a rotary fluid apparatus, in combination, a rotatable hub, aseries of relatively flat circular disks pivotally mounted in said huband rotatable relatively thereto about axes different from the axis ofrotation of said hub; said disks passing through slots in the hub wallformed to provide small clearance around said disks, and the axis ofsaid disks being inclined in a direction at an angle to the axis of hubrotation when projected in a plane containing said hub axis, and alsoinclined with respect to said plane.

LEWIS FERRY MOODY.

